Plant Cell Reports最新文献

Key message: As a repressor of SA pathway, ERF3 is induced by pathogens to repress the expression of SA pathway genes and promote JA-mediated wounding and ABA-mediated abiotic-stress responses in defense response. ERF/AP2 family transcription factors play crucial roles in plant growth, development, and stress responses. However, the function of most family members remains unclear. Here, the role of ERF3 in disease resistance was investigated by transcriptomic sequencing. erf3 mutants are more resistant, whereas ERF3-overexpression (ERF3-OE) plants are more susceptible to bacterial pathogen Pst DC3000 than wild type. Through transcriptomic sequencing, we identified 175 differentially expressed genes (DEGs) between erf3 and wild-type plants, including 44 up-regulated (erf3up) and 131 downregulated genes (erf3down) in erf3. GO analysis showed that erf3up DEGs were most significantly enriched in defense response, including SA pathway marker genes PR2 and PR5, and defense genes RLP23, WRKY53, and RAV2 which play positive roles in resistance against Pst DC3000. By contrast, erf3down DEGs were significantly enriched in response to wounding/jasmonic acid, response to abscisic acid/water deprivation, etc., but no components of JA pathway disease resistance were down-regulated by loss of ERF3 function, indicating ERF3 positively regulate JA-mediated wounding and ABA-mediated abiotic-stress responses upon pathogen infection. ERF3 is induced by Pst DC3000, SA and JA, and ERF3 protein was detected to enrich on PR5 and RAV2 which harbor DRE boxes on the promoter and are up-regulated in erf3 mutants. Overall, ERF3 functions as a repressor in SA pathway disease resistance, and upon pathogen infection, ERF3 is induced to repress the expression of SA pathway genes and promote JA-mediated wounding and ABA-mediated abiotic-stress responses. Our work provides novel insights into the potential of exploiting ERF3 function to enhance plant disease resistance.

Key message: OsPUB36, a root-preferential E3 ubiquitin ligase, modulates reactive oxygen species homeostasis and regulates rice root development, affecting primary root and root hair growth. Root development is tightly regulated by spatial gradients of reactive oxygen species (ROS), which coordinate transitions from cell division to elongation and differentiation. Through phylogenetic meta-analysis, we identified a root-preferential subclass of class III PUB E3 ubiquitin ligases (OsPUB31-OsPUB37). Among them, OsPUB36 was selected as a representative gene for functional characterization. Overexpressing OsPUB36, an endoplasmic reticulum (ER)-localized protein, resulted in shortened primary roots and elongated root hairs. RNA-seq and proteomic analysis of root hairs from plants overexpressing OsPUB36 revealed significant upregulation of class III peroxidases, key enzymes involved in ROS homeostasis. Histochemical staining confirmed enhanced levels of hydrogen peroxide (H₂O₂) in root hair. However, the loss-of-function mutants (ospub36 and ospub35 ospub36) displayed no obvious phenotypes, suggesting functional redundancy within these gene subclasses. While yeast two-hybrid screen did not identify direct targets related to ROS or root development, RNA-seq, proteomic, and histochemical analyses suggest that OsPUB36 and other class III PUBs modulate ROS homeostasis.

Key message: A TRV-based and bud-vacuum-infiltration-mediated VIGS system achieves an effective gene silencing across multiple varieties under defined optimal conditions in Tartary buckwheat (TB). TB is a valuable grain rich in bioactive flavonoids, but the absence of a genetic transformation system has hindered in vivo functional verification of its genes. Virus-Induced Gene Silencing (VIGS) offers a rapid and efficient alternative for gene studies. This study established and optimized a VIGS system for TB using the phytoene desaturase gene (FtPDS) as a reporter, whose silencing causes photobleaching (albinism). Bioinformatic analysis revealed that FtPDS has a 6,127 bp genomic sequence and a 1,713 bp cDNA, having high similarity to rice phytoene desaturase (OsPDS). We compared two infiltration methods for VIGS delivery: leaf injection into TB cotyledons versus bud vacuum infiltration of germinated seeds, and found the bud vacuum method was more effective, yielding a higher albinism rate (28.9% vs. 12.3%). Using response surface methodology, we determined optimal conditions including germination length at 1.5 cm, the Agrobacterium OD₆₀₀ at around 1.0, the infiltration duration for 5 min and post-infiltration cultivation temperature at 20 °C, achieving a silencing efficiency ranging from 27% to 62.05%. The applicability of this system was validated by silencing FtUFGT163 and FtMYB5, key genes in rutin biosynthesis. Silencing FtUFGT163 reduced its expression by 81.7%-89.74% and decreased rutin content by 22.22%-36.18%, while FtMYB5 silencing lowered its expression by 76.77%-85.64% and reduced rutin content by 22.19%-33.89%. Additionally, FtMYB5 silencing downregulated several genes in the flavonol synthesis pathway, including FtC4H, FtCHS, FtCHI, FtF3H, FtPAL, Ft4CL, FtF3'H, and FtFLS, confirming its regulatory role. Overall, this efficient and stable VIGS system provides a powerful platform for functional genomic studies in TB.

Key message: RNA-seq and virus-induced gene silencing experiments have demonstrated that the transcription factor SlWRKY6 affects tomato cold tolerance by responding to melatonin signaling and influencing photosynthesis. Cold stress severely impairs photosynthesis, limiting tomato growth during off-season cultivation. Melatonin (MT) has been shown to enhance plant cold tolerance, yet its regulatory mechanism for maintaining photosynthetic performance remains unclear. In this study, we demonstrated that MT treatment improved the photochemical efficiency of photosystem II (PSII) and stabilized the Calvin cycle under cold stress, thereby enhancing electron transfer, CO₂ fixation, and overall photosynthetic capacity. Notably, transcriptome analysis identified SlWRKY6 as a melatonin-responsive transcription factor that positively regulates photosynthesis under cold conditions. Functional validation using virus-induced gene silencing (VIGS) revealed that silencing SlWRKY6 significantly suppressed photosynthesis-related gene expression, impaired photochemical reactions, and reduced carbon assimilation, ultimately decreasing cold tolerance. Importantly, exogenous MT application was able to partially restore these photosynthetic processes, even under SlWRKY6 silencing. These findings highlight that MT may enhance cold tolerance in tomato via SlWRKY6 as a key regulatory node through modulating the photosynthetic pathway, providing new insights into MT-mediated cold stress adaptation mechanisms in crops.

Key message: J13 imparts drought tolerance to A. thaliana by accelerating plant auxin-dependent, auxin-amino acid conjugation pathway. Plant mutants defective in this pathway do not respond favorably to the bacterium under drought. The precise roles of plant auxin signaling and metabolism in beneficial plant-microbial interaction, especially for abiotic stress tolerance, have not been clearly understood. In this study, we have used the drought-alleviating PGPR strain, Bacillus endophyticus J13 and investigated its impact on auxin signaling and homeostasis in Arabidopsis thaliana, under drought stress. While drought stress elevated the levels of free auxin in A. thaliana plants, J13 inoculation under drought stress lowered the auxin levels in the plants. However, the decreased auxin levels in the drought-stressed plants were accompanied by an increase in the expression of key auxin biosynthetic genes. To understand the reason for this discrepancy, we investigated the role of J13 in auxin conjugation in A. thaliana under drought stress, and observed that, J13 upregulated the transcript levels of genes involved in auxin-dependent auxin conjugation in the plants. A. thaliana mutants deficient in auxin-dependent auxin conjugation (GH3.3) and auxin signalling (axr2-1) did not respond favourably to J13 inoculation under drought conditions. Rather, these mutants exhibited enhanced susceptibility to drought conditions under J13 inoculation. To understand the underlying mechanism of this enhanced drought susceptibility in the mutants, we studied the impact of J13 on the expression of selected genes of salicylic acid-mediated immune signaling in the plants. These mutants exhibited J13-specific modulation in the expression of these genes. Our study thus establishes the importance of auxin-dependent auxin conjugation as a key mechanism of PGPR-mediated drought amelioration in plants.

Key message: The transcription factor CiMYB4 enhances the tolerance of Chrysanthemum indicum to cadmium stress by regulating the CiPCS gene and promoting the synthesis of phytochelatins. Phytochelatins (PCs) are crucial for enhancing plant tolerance and detoxifying heavy metals such as cadmium (Cd). However, the functional roles and regulatory mechanisms of phytochelatin synthase (PCS), the enzyme responsible for PC synthesis in chrysanthemum, remain largely unexplored. In this study, we successfully isolated and cloned a PCS gene from Chrysanthemum indicum, designated as CiPCS. Subcellular localization analysis revealed that CiPCS is localized in both the cytoplasm and nucleus, and Cd stress significantly upregulated its expression. The overexpression of CiPCS enhanced the tolerance of C. indicum to Cd by increasing the activity of antioxidant enzymes and reducing membrane lipid peroxidation. Further analysis indicated that CiPCS is directly regulated by the transcription factor CiMYB4, promoting the synthesis and accumulation of plant chelating peptides (PCs), enhancing the chelation of Cd ions and thereby reducing the toxic effects of Cd on cells. In summary, our study elucidates the regulatory mechanism by which C. indicum responds to Cd stress.

Key message: This is the first report on the identification and fine-mapping of yellow mosaic disease resistance locus, qMYMIV14.1, on chromosome 14 using integrative genomic approaches in interspecific soybean populations. Yellow mosaic disease (YMD) is a major viral threat to soybean production in Asian and Southeast Asian countries. Field screening of the disease was performed at Ludhiana; a YMD hot spot and its causative agent, mungbean yellow mosaic India virus (MYMIV, Begomovirus vignaradiataindiaense) was detected and validated as the causal agent through PCR and sequence analysis. Genetic assessment was conducted on 1784 F₂ plants derived from a cross between the susceptible cultivated soybean (Glycine max cv. 'NRC 94') and a resistant wild accession (Glycine soja accession 'PI 393551'). The segregation ratio indicated that YMD resistance is controlled by four dominant genes, three of which confer resistance, while one inhibitory gene suppresses this resistance. Test of allelism performed on direct and reciprocal crosses [SL 958//JS 335/PI 393551 (BC₅F₆)] across F₁, F₂, and F₃ generations revealed that genes in cultivated and wild soybean were non-allelic with no maternal effect. Bulked segregant analysis (BSA) initially identified eight markers (Satt157, BARCSOYSSR_14_0441, BARCSOYSSR_14_0445, BARCSOYSSR_14_0448, BARCSOYSSR_14_0455, BARCSOYSSR_14_1416, BARCSOYSSR_14_1417 & BARCSOYSSR_14_1516) linked to resistance. Traditional QTL mapping revealed three novel QTLs on chromosome 14. Combined results from QTL-seq, a genome-wide association study, and QTL mapping consistently identified a major and stable locus, qMYMIV14.1, spanning the 46.55-48.70 Mb region on the long arm of chromosome 14. This is the first QTL detected from an interspecific cross which explained for 27.81-68.01% of phenotypic variance. Two candidate genes, Glyma.14G173300 and Glyma.14G173600, encoding leucine-rich repeat proteins, were identified within this locus. These findings provide valuable genomic resources for marker-assisted selection and breeding of soybean cultivars with durable YMD resistance.

Key message: Our results highlight the key role of NaMYC2a/b in regulating trypsin protease inhibitor activity after insect feeding by controlling the expression of NaPI, NaKTI2, and NaPI-like. When attacked by insect herbivores, Nicotiana attenuata plants activate jasmonate (JA) signaling, and increase trypsin protease inhibitor (TPI) activities by switching on the transcription of various protease inhibitor (PI) genes, such as NaPI and NaKTI2. However, how PI genes are regulated during insect feeding remains unclear. Here we identified a new PI, NaPI-like, that confers Spodoptera litura resistance. NaPI-like shares low sequence identity to NaPI. However, its expression could be specifically and highly induced by S. litura oral secretion (OS). TPI activity was increased by NaPI-like overexpression, and was reduced by silencing NaPI-like. Accordingly, the generalist S. litura performed better in NaPI-like-silenced plants. Further study revealed that the expression levels of NaPI, NaPI-like, and NaKTI2 were all strongly elicited by treatment with methyl JA or wounding plus S. litura oral secretion (W + OS) in wild-type (WT) plants. However, they were induced to a much lesser extent in JA-deficient irAOC plants with W + OS treatment, suggesting that these three PI genes are regulated by JA signaling. Finally, we demonstrated that co-silencing NaMYC2a and NaMYC2b significantly reduced TPI activity, resulting in decreased insect resistance in N. attenuata. EMSA and Dual-LUC assays revealed that NaMYC2a/b regulates the expression of NaPI and NaKTI directly, and NaPI-like indirectly. Our results highlight the diversity of PI genes elicited by insect, and the key role of NaMYC2a/b in regulating TPI activity after insect feeding by controlling NaPI, NaPI-like, and NaKTI2 expression. Thus, our data provide new insights into the regulation of PIs during insect feeding.

Key message: Our results highlight the key role of NaMYC2a/b in regulating trypsin protease inhibitor activity after insect feeding by controlling the expression of NaPI, NaKTI2, and NaPI-like.

Key message: Screening of salt-tolerant alfalfa varieties, identification of key genes and verification of gene function. Screening and breeding salt-tolerant alfalfa varieties is crucial for the development and utilization of saline-alkali land. This study employed a comprehensive evaluation system to examine the response of various alfalfa germplasms to different salt concentrations during the germination and seedling stages. The classification of germplasms was achieved by integrating salt tolerance indicators across both phases, identifying the highly salt-tolerant cultivar 'Pegasus' and the salt-sensitive cultivar 'Fort'. Transcriptome analysis revealed significant differences in gene expression between 'Pegasus' and 'Fort' under salt stress conditions. This identified 24 key candidate genes associated with alfalfa salt tolerance. Further analysis showed that the differential pathways between the tolerant and sensitive varieties involved metabolism and ion transport. The selected differential gene, MsELIP, was heterologously expressed in Arabidopsis. Compared to wild-type plants, the germination rate, main root length, chlorophyll content, and antioxidant capacity of the overexpression lines increased significantly under salt stress conditions. These findings provide germplasm resources for breeding salt-tolerant alfalfa and a theoretical foundation for elucidating the molecular mechanisms of salt tolerance in alfalfa.

Key message: Constitutive expression of AtYUC1 in potato enhances branching and tuber production through upregulation of StARF1 and StARF5, which suppress StBRC1a expression. Branching is a crucial determinant of plant architecture, optimizing light capture, improving environmental adaptability, and enhancing crop yield. Potatoes (Solanum tuberosum) possess above-ground stems and modified stems. To investigate the effect of AtYUC1 in these processes, we generated transgenic potato lines constitutively expressing heterologous AtYUC1 and performed phenotypic and molecular analyses. Elevated auxin levels in the transgenic lines enhanced branching, plant height, stolon number, and above-ground biomass. The number of tubers was also significantly higher compared to wild-type plants. Molecular analysis revealed significant upregulation of StARF1 and StARF5. In addition, StBranched1a (StBRC1a) expression was significantly downregulated in these lines. Auxin treatments further confirmed concentration-dependent modulation of StBRC1a and StBRC1b expression. Further investigations demonstrated that StARF1 and StARF5 bind to the promoter region of StBRC1a, repressing its expression and thereby promoting branching. This study provides valuable insights into the hormonal regulation of branching in potatoes and underscores the potential of genetically manipulating auxin biosynthesis pathways to enhance potato yield.